Invadopodia are thin cell membrane extensions detected in aggressive tumor cells and defined by their role in localized extracellular matrix degradation. The goal of the proposed research is to determine the involvement of invadopodia in breast cancer cell migration through 3D collagen networks and to determine which aspects of invadopodia function are critical for invasion. In 3D culture models, the candidate will 1) measure invadopodia-like membrane extensions, 2) determine the relationship between membrane extension and invadopodial complex formation, 3) develop a mechanistic model of the interconnections between cell-matrix adhesions, filopodia, invadopodia and to localized force exerted on the ECM and matrix degradation, and 4) determine the role of invadopodia in the response of chemotactic tumor cells to controlled chemoattractant gradients. As a result, the candidate will have built a unique set of tools to quantitatively model invasive cell behavior in 3D, and the research should produce new insights into the multi-faceted role of invadopodia in invasion. The proposed work provides the candidate with an ideal opportunity to achieve his career transition goal by 1) education in cancer cell biology, 2) training in in vitro cell and molecular techniques including cell culture, manipulation of plasmids and siRNA, transfection, and use of in vitro assays of cellular behavior focusing on cell motility and invasion, and 3) interaction with successful cancer cell biologists, including the mentor Dr. Susette Mueller, in the setting of the Lombardi Comprehensive Cancer Center. Relevance: Several cell surface features are thought to be required for migration and invasion: filopodia and lamellipodia formation, matrix-cell adhesions, and invadopodia. Yet the contribution of adhesion and matrix degradation at these localized sites to cellular invasion has not been studied adequately in a 3D cell culture environment. Some critical components of typical cancer cell behavior can likely only be reproduced in the context of a 3D environment. Experiments proposed here are important prerequisites to imaging tissue ex vivo and in vivo where the contribution of other complex effects of the microenvironment can be explored. An understanding of the significance of invadopodia for altering and moving through the extracellular matrix may identify new targets for intervention to prevent migration and metastasis, which would ultimately improve survival. Quantitative imaging, feature-tracking, and displacement-measurement in a 3D polymer matrix is challenging and requires researchers such as the candidate with experience in optical system design, image analysis, and quantitative experimental design and interpretation.